Deciding between mac mini and iMac

I am trying to decide between the iMac and the mac mini. I'm not sure if the gpu in the mac mini is good enough for my needs.

I'm mostly going to be using it for video editing (possibly iMovie depending on if it's sufficient, or pinnacle studio), photoshop, illustrator, indesign.

The mac mini only goes up to 2.6GHz Quad-Core Intel Core i7 and the iMac goes up to 3.6GHz quad-core Intel Core i5. Does it matter that the mac mini has a slower processor but is i7 and the iMac has a faster processor but is i5? What speed do I need? I don't really want to overspend.

Also, do I need 8gb or 16gb of ram? And is the 1tb fusion drive basically the same as having a 128gb ssd and a 872gb hd?